MeiLi 9- Graphic Design Mural Catastrophe

So right now I'm taking graphic design 2 because I want to be a graphic designer when I’m older. Currently we’re working on a project where we had to choose a teacher to work with as our “client” to make a mural that is going to go on a wall in the hallway. The project started weeks ago, but (and of course there's a but) there's been a few problems with my mural. When we first began the project, I was under the assumption that I was working with a specific teacher when in reality I wasn't. The misunderstanding is COMPLETELY my fault, but I was almost halfway finished with my design and project being complete when I found out the teacher that I had been working with was not my actual client. In an entire series of events, I ended up having to redo the project completely and today was the first day I had a first sketch done since I didn't have a final for sure quote until yesterday. I completely fell in love with my first design, but luckily I still get to put it up in the school which I am beyond thankful for. However this mishap set me so far back. The final file is due to the signage company on the 24th of February, which is four days away, and I don't even have a final design done. Not to mention how tedious doing a design like this is on Adobe Illustrator. I'm terrified that I'm not going to be able to get it done in time or it's not going to be my best work ever. But we're pushing through. The new quote I’m working with is unbelievably unique and designing it has been so much fun thus far. I began the new design with a negative outlook, but I've been working on changing my mindset and I've made huge progress. I'm just very stressed about the whole project. It's a 19ft by 2ft space and I want it to look as amazing as possible.
The benefit of this situation is how real it is. Ms. Stager, the teacher of my graphic design class, said things like this occur all the time in the real world, and it's a good experience to have and be able to work through. It's just frustrating to have to restart something I was super excited about. But nonetheless, I’m pushing through and falling in love with the new design little by little every time I sit down to work on it. What would you do if you had to completely start over a week before the due date on a huge project? And does anyone have ANY advice for me?? I need something to calm me down about the whole thing. I feel like Dory, continuously telling my self to: